Weed Spotter Archive
Water Hyacinth (Eichhornia crassipes)
Mosca, Alamosa County
While visiting the Great Sand Dunes National Park last summer, Steve Lundt saw a canal covered in Water hyacinth with only some chicken wire holding it back from the rest of the San Luis Valley.
Water hyacinth is an invasive aquatic plant that has been a problem in waterways in the southern US and California. This plant forms dense stands that interfere with the flow of water and severely alters the habitat for aquatic organisms. This is one of the worse aquatic weeds worldwide.
More Information and pictures
Japanese knotweed - Arvada, Jefferson County
submitted by Vic Elam, Refuge Manager
Two Ponds National Wildlife Refuge
Vic Elam recently identified two infestations of Japanese knotweed at Two Ponds and along the Croke and High Line canals which flow through the refuge. The infestations are being treated. Link to more information
Syrian Beancaper - Mesa County
submitted by Jude Sirota
In June of this year, Jude Sirota identified a patch of Syrian beancaper (Zygophyllum fabago L.) along the westbound I-70 right-of-way about 2 miles east of Fruita. In reviewing the CSU Herbarium records, this plant was found near this area in the mid-1950's.
Syrian beancaper is a perennial that spreads by seed and root fragments. It is well suited to dry areas.
More information and pictures
Black Henbane - Idaho Springs, Clear Creek County
submitted by Sandra Butler, landowner
Sandra Butler discovered three Black henbane plants growing in the area of her newly constructed leach field; she removed the plants.
Although Black henbane is found in some parts of the state, it is not known to occur in Idaho Springs.
Japanese Knotweed - Boulder County
submitted by Tim D'Amato
In August 2005, Vannelle Carrithers with DOW Chemical, was touring plots with George Beck in and around Boulder County. Vannelle spotted the knotweed off of Hwy 66, just east of the intersection with Hwy 287. She was very alarmed because of the invasivness of the plant in the Pacific Northwest where she's from. I was notified, and in turn notified CDOT, the responsible managing agency for the right-of-way along a state highway. Within a week CDOT sprayed the area (approx 200 sq ft) with a 1 qt rate of Tordon + 1 qt 2,4-D. The plants immediately turned necrotic, I'll monitor this spring for any regrowth.
Blue weed or Viper's bugloss (Echium vulgare) - Kremmling, CO
submitted by Stephen Enloe - University of Wyoming
Stephen Enloe discovered Viper's bugloss along the roadside just south of town (pretty close to the railroad tracks too). He notified Eric Lane and George Beck.
Elongated mustard (Brassica elongata)
submitted by Larry Walker, Chaffee County Weed Supervisor
Elongated mustard was found in the spring of 2004 along the Fremont/Chaffee countyline north of highway 50 and the Arkansas River. The site is 5 miles east of Salida. To date, this is the only site known in Colorado and has spread to around 100 acres. (The plant is also found along highway 50 in Nevada where Dr. Young believes it is becoming very invasive.) The plant can grow as an annual, biennial or perennial with the base of the stalk breaking off in late summer to early fall to be dispersed by the wind.